diff --git a/ts/receiver/closedGroups.ts b/ts/receiver/closedGroups.ts
index 8e55bb09a..831c81fc6 100644
--- a/ts/receiver/closedGroups.ts
+++ b/ts/receiver/closedGroups.ts
@@ -51,7 +51,7 @@ export async function getAllCachedECKeyPair(groupPubKey: string) {
     cacheOfClosedGroupKeyPairs.set(groupPubKey, keyPairsFound);
   }
 
-  return keyPairsFound;
+  return keyPairsFound.slice();
 }
 
 /**